Blue dye.



UNITED STATES PATENT 0mm RENE BOHN, OF MANNHEIM, GERMANY, ASSIGN OR TO THE BADISOHE ANILIN AND SODA FABRIK, OF LUDWIGSHAFEN, GERMANY.

SPECIFICATION forming part of Letters Patent No. 627,896, dated June 27,1899.

Application filed November 16, 1898. Serial No. 696.622. (Specimens.)

To aZZ whom it may concern.-

Be it known that I, RENE BOHN, doctor of philosophy, a citizen of the Swiss Republic, residing at Mannheim, in the Grand Duchy of Baden and Empire of Germany, have invented new and useful Improvements in the Manufacture of a new Blue Dyestuff, of which the following is a specification.

In the preparation of naphthazarin 1.1-dinitro-naphthalene is treated with sulfuric acid, preferably in the presence of a reducing agent, such as zinc orsulfur. This treatment results in the production of a product which is soluble in water, giving a bright blue solution, and which is known as naphthazarin intermediate product. (See Ber. IV, 439.) If this body be treated with a'reducing agent, a leuco product is obtained.

My present invention relates to the production of anew and most beautiful blue coloring-matter by sulfonating this leuco compound.

My new coloring-matter has the valuable property of yielding very clear blue shades on mordanted andon un mordantedwool. These shades are of a purity which could hitherto only be achieved with the aid of 'anilin colors.

It dis are'by weight. Add about ten (10) parts of leuco compound, which can be obtained as hereinbefore set forth, to one hundred (100) parts of fuming sulfuric acid, (containing about twenty-three per cent. free S0 Heat the mixture while stirring for about two (2) hours at a temperature of 100 centigrade. Allow the melt to cool,.and then pour it onto about two thousand (2,000) parts of ice, and precipitate the coloring-matter with common salt.

My new coloring-matter can be applied in dyeing either as suchthat is, directly in the form obtained on following the above example-or it can be applied in the form of its leuco compound, which can be obtained in the well-known way by reducing the coloringmatter .With, for instance, stannous chlorid and hydrochloric acid, or sodium hyposulfite.

The coloring-matter itself and its leuco compounds are for practical purposes the equivalents of one another, and this application is intended to cover the new product in both forms.

Now what I claim is-- As a new article of manufacture the blue colorwith concentrated sulfuric acid and a magenta-red color on heating with dilute sulfuric acid, all as hereinbefore described.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

RENE BOHN.

Witnesses:

GUSTAV L. LICHTENBERGER, ADOLPH REUTHLINGER. 

